diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index aba9c9a..2d6228a 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -621,9 +621,7 @@
 endfunc
 
 func Test_diffexpr()
-  if !executable('diff')
-    return
-  endif
+  CheckExecutable diff
 
   func DiffExpr()
     " Prepent some text to check diff type detection